A novel and facile method for selective reduction of 3-nitro-4-methoxy-acetylaniline (NMA) to 3-amino-4-methoxy-acetylaniline (AMA) was suggested by using Cuo nanoparticle as the catalyst and NaBH4 as hydrogen source in water. The Cuo nanoparticles were synthesized by the wetness chemical reduction method. The particle sizes of Cuo nanoparticles significantly affected their catalytic activities in NMA reduction. When the Cuo nanoparticles with the average particle size of 5.9nm synthesized in the presence of cetyltrimethyl ammonium bromide as the organic modifier were used as catalysts, the AMA selectivity reached 99.6% at the NMA conversion of 100% after reacting at 35°C for 30min. The Cuo nanoparticles had good recycling performance. A power-function type reaction kinetic model well fitted the experimental data, r=−dCN/dt=kCN0.4CB1.1. The reaction activation energy was 93.1kJmol−1.